前言
HttpClient在Web調(diào)用中具有廣泛的應(yīng)用，而為它添加默認(rèn)請(qǐng)求頭是我們經(jīng)常遇到的需求，本文介紹4種為HttpClient添加默認(rèn)請(qǐng)求頭的方式。下面話不多說(shuō)了，來(lái)一起看看詳細(xì)的介紹吧
第一種方式
直接在創(chuàng)建的HttpClient對(duì)象的DefaultRequestHeaders集合中添加報(bào)頭。
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class Program{ static Task Main()=> SendAsync1(); private static async Task SendAsync1() { var httpClient = new HttpClient(); AddDefaultHeaders(httpClient); } private static void AddDefaultHeaders(HttpClient httpClient) { httpClient.DefaultRequestHeaders.Add("x-www-foo", "123"); httpClient.DefaultRequestHeaders.Add("x-www-bar", "456"); httpClient.DefaultRequestHeaders.Add("x-www-baz", "789"); }} |
第二種方式
對(duì)于.NET Core應(yīng)用來(lái)說(shuō)，我們更推薦的做法是采用依賴注入的方式，利用IHttpClientFactory來(lái)創(chuàng)建HttpClient對(duì)象，那么我們?cè)谶M(jìn)行相關(guān)服務(wù)注冊(cè)的時(shí)候就可以設(shè)置默認(rèn)請(qǐng)求報(bào)頭。
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class Program{ static Task Main()=> SendAsync2(); private static async Task SendAsync2() { var services = new ServiceCollection(); services.AddHttpClient("", AddDefaultHeaders); var httpClient = services .BuildServiceProvider() .GetRequiredService<IHttpClientFactory>() .CreateClient(); } private static void AddDefaultHeaders(HttpClient httpClient) { httpClient.DefaultRequestHeaders.Add("x-www-foo", "123"); httpClient.DefaultRequestHeaders.Add("x-www-bar", "456"); httpClient.DefaultRequestHeaders.Add("x-www-baz", "789"); }} |
第三種方式
由于HttpClient在發(fā)送請(qǐng)求的時(shí)候會(huì)利用DiagnosticSource對(duì)象發(fā)送相應(yīng)的診斷事件，并且將作為請(qǐng)求的HttpRequestMessage對(duì)象作為請(qǐng)求事件內(nèi)容負(fù)載。我們可以訂閱該事件，在請(qǐng)求被發(fā)送之前將其攔截下來(lái)，并添加相應(yīng)的請(qǐng)求頭即可。
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class Program{ static Task Main()=> SendAsync3(); private static async Task SendAsync3() { Func<object, HttpRequestMessage> requestAccessor = null; DiagnosticListener.AllListeners.Subscribe(listener => { if (listener.Name == "HttpHandlerDiagnosticListener") { listener.Subscribe(kv => { if (kv.Key == "System.Net.Http.HttpRequestOut.Start") { requestAccessor ??= BuildRequestAccessor(kv.Value.GetType()); var request = requestAccessor(kv.Value); AddDefaultHeaders(request); } }); } }); var httpClient = new HttpClient(); static Func<object, HttpRequestMessage> BuildRequestAccessor(Type payloadType) { var property = payloadType.GetProperty("Request", BindingFlags.Instance | BindingFlags.Public); var payload = Expression.Parameter(typeof(object)); var convertedPayload = Expression.Convert(payload, payloadType); var getRequest = Expression.Call(convertedPayload, property.GetMethod); var convert = Expression.Convert(getRequest, typeof(HttpRequestMessage)); return Expression.Lambda<Func<object, HttpRequestMessage>>(convert, payload).Compile(); } } private static void AddDefaultHeaders(HttpRequestMessage request) { request.Headers.Add("x-www-foo", "123"); request.Headers.Add("x-www-bar", "456"); request.Headers.Add("x-www-baz", "789"); }} |
第四種方式
上面這種方式可以采用強(qiáng)類型編程方式，具體的代碼如下。
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class Program{ static Task Main()=> SendAsync4(); private static async Task SendAsync4() { DiagnosticListener.AllListeners.Subscribe(listener => { if (listener.Name == "HttpHandlerDiagnosticListener") { listener.SubscribeWithAdapter(new HttpClientListener()); } }); var httpClient = new HttpClient(); } private sealed class HttpClientListener { [DiagnosticName("System.Net.Http.HttpRequestOut.Start")] public void OnSend(HttpRequestMessage request) => AddDefaultHeaders(request); //Must subscribute the System.Net.Http.HttpRequestOut event. [DiagnosticName("System.Net.Http.HttpRequestOut")] public void OnSend() { } } private static void AddDefaultHeaders(HttpRequestMessage request) { request.Headers.Add("x-www-foo", "123"); request.Headers.Add("x-www-bar", "456"); request.Headers.Add("x-www-baz", "789"); }} |
總結(jié)
以上就是這篇文章的全部?jī)?nèi)容了，希望本文的內(nèi)容對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值，謝謝大家對(duì)服務(wù)器之家的支持。
原文鏈接：https://www.cnblogs.com/artech/p/add-headers-for-httpclient.html
